Valve motion indicator for steam engines



3 SheetsSheet 1.

. J. MILLIS. VALVE MOTION INDICATOR FOR STEAM ENGINES. No. 481,671.Patented Aug. 80, 1892.

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(No Model.) 3 Sheets-Sheet 2.

J. MILLIS.

VALVE MOTION INDICATOR FOR STEAM ENGINES.

No. 481,671. Patented Aug. 30, 1892.

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(No Model.) 3 SheetsSheet 3.

J. MILLIS. VALVE MOTION INDICATOR FOR STEAM ENGINES.

No 481,671. Patented-Aug. 30, 1892.

UNTTED STATES PATENT OFFICE.

JOHN MILLIS, OF THE UNITED STATES ARMY.

VALVE-MOTION INDICATOR FOR STEAM-ENGINES.

SPECIFICATION forming part of Letters Patent No. 481,671, dated August30, 1892.

Application filed May 9, 1891. Serial No. 392,217. (No model.)

T0 whom it may concern,-

Be it known that I, JOHN MILLIS, a citizen of the United States, and anofficer in the United States Army, now stationed at New Orleans,Louisiana, have made certain new and useful Improvements in Valve-MotionIndicators for Steam-Engines and other Machines, of which the followingis a specification.

Heretofore various forms of stean'i-engine indicators have beenemployed, by which the varying pressure and action of the steam in theengine-cylinder has been shown by means of a diagram traced by a pencilon a sheet of paper carried upon a small rotating cylinder or barrel,which forms a part of the indicator, the instrument being so attached toand connected with the engine that the motion of the barrel of theindicator corresponds to the motion of the piston of the engine, whilethe movement of the pencil which traces the diagram is efiected by themotion of a small piston in the indicator, whose motion corresponds tothe Varying pressure in the enginecylinder. So far as I know, however,the action of the valve-gear and valves which control the admission andexhaust of the steam has heretofore only been obtained theoretically bymodels, drawings, or calculations, or by certain crude devices appliedto the engine which can be used only in special cases, and which giveonly approximate results.

The object of my invention is to provide a valve-motion indicator forsteam-engines or other machinery by means of which anautomatically-drawn diagram is produced which shows the movements of thevalve-gear and valves relatively to the motion of the piston when theengine is working under the conditions of actual service and whichenables the exact relative motion and action of the valves and anyportion of the valve-gear or other moving parts to be shown with greatprecision and to be readily studied. Preferably the valve-motion diagramshould be drawn on the same card and at the same time as the regularsteam-diagram, so that the two diagrams may be readily compared frompoint to point. This is particularly desirable in the case of engineshaving an automatic cut-off form of valve-gear, where the steam-diagramand the action of the valves are constantly changing with variations ofload. My valve-motion regular form of steamindicator now in the market.

Figure 1 is a front elevation of the combined steam-indicator andvalve-motion indicator, the pencil of the valve-motion indicator beingshown in its uppermost position. Fig. 2 is a side elevation, the pencilof the valve-motion indicator being shown in alower position. Fig. 3 isa rear View, the barrel and steam-indicator being partly broken away.Fig. 4 is a top plan of the entire apparatus. Fig. 5 is a detail showingthe valve-indicator disconnected from the steam-indicator, as it is usedwhen the valve-motion diagram only is to be drawn. Figs. 6 and? arereproductions of diagrams made by the instrument.

The same letters and numerals indicate the same or similar parts in thedifferent figures.

A is the chamber of the steam-indicator, into which the steam isadmitted from the engine-cylinder, to which it is removably attached bythe threaded union B, working upon the thread a of the steam-cock below.By turning the union by means of the handles 1) b the indicator and allits attachments are disconnected from the engine and readily removedtherefrom.

C is the card-bearing cylinder or barrel carrying the card 0, upon whichboth steam and valve-motion diagrams are drawn.

The steam-in dicator is of ordinary construction, being provided with apiston and spring in the cylindrical chamber A, a piston-rod d, and apencil-carrying device with parallel motion eff" g, the pencil-point 7ibeing carried at the extreme outer end of the bar 6. The post f andlinkf are mounted upon projections from a sleeve 2', which surrounds thechamber A and which is turned into the position shown in Fig. l, wherethe pencil h comes in contact with the card 0 or away from the card, asdesired, by the adjustable screwhandlej passing through post 76, mountedon and extending through one of the projections of said sleeve, as shownmore particularly in Figs. 1 and 4. The handle 7' is turned or fedthrough said post 7t" by means of the screwthread on said handle to suchadistance that when the pencil-carrying device is moved toward the cardenough to touch the same the extreme end of said screw-threaded handlejcomes against the stop Z, which is provided on the arm m, which supportsthe cardcarrying cylinder and which is in turn supported by being madeintegral with the clamp n, which surrounds the chamber A below themovable sleeve 2' and is held immovable and tightly grasping saidchamber A by the screw and socket 0. Of course as the pencil wears awaythe adjustable handle j is turned outward proportionately, so as toallow the pencil-carrying device to swing in far enough to have thepencil-point continue to touch the card.

The chamber A is provided with the usual drip-openings p.

The card-carrying cylinderor barrel 0 is of ordinary construction,except that it is preferably made somewhat longer than usual. It issupported by the arm m of the clampingsleeve n.

The card 0 consists, as usual, of a piece of paper wrapped around thecylinder and held by means of the clamp-strip s, hinged attand extendingup to the top of the cylinder, where it is engaged by the stops u a.

The catch 1;, Fig. at, mounted upon the arm m, supporting the barrel, isprovided to engage the teeth w around the base of the barrel and preventany revolution of the barrel when it is desired to have the same remaininactive for the removal of the card or for any other purpose.

Persons skilled in the art know without further explanation that thepencil-point 7L as it moves up and down in the direction of the verticalarrow shown in Fig. 1 in accordance with the varying pressure of thesteam upon the piston and spring in the chamber A of the indicator,while the card 0 is alternately rotated in the direction of thehorizontal arrows by a cord g, which is connected by suitable devices tosome part of the engine whose motion corresponds to that of theengine-piston, and by a retractile spring, will indicate the action ofthe steam in the engine-cylinder.

As before stated, there is nothing peculiar in the constructiondescribed, the steam-indicator shown and described being one of the manywell-known forms in the market, to any of which my invention of avalve-motion indicator could be readily applied.

1 now come to the description of my valvemotion indicator, which, as Ibefore stated, may be used independent of the steam-indicator or as anattachment thereto, as shown in the drawings. The valve-motion diagramis traced by a pencil-point D, moving parallel to the axis of theindicator-barrel similarly as in the case of the steam-diagram.Preferably this pencil-point D should be so placed with reference to thepencil-point 7L of the steam-indicator that both move in the samevertical line when bearing on the card 0, and to accurately effect thisadjusting jam-nuts d are provided on each side of the holder 1 of thepencil-point D, as shown. The pencilpoint D of the valve-motionindicator is thus adj ustably mounted near the end of an arm E, which isstiffened and supported by the brace E. The arm and brace are attachedto a block or cross-head S, which slides freely in the rods F, theselatter being parallel to the axis of the indicator-barrel. These rodsare attached to a tube or sleeve G, which fits closely over an innertube, but is sutliciently free to enable it to be easily turned aboutthis inner tube. The inner tube is rigidly supported in a hub or baseII, (see Fig. 2,) attached to the arm m, before spoken of as supportingthe barrel C, and from the upper end of the inner tube projects an arm,on which the pulley I is mounted, and the outer end of which armsupports the top bearing of the axis of the barrel (3, as shown, beingconnected thereto by the thumb-screw T. Below the base II is aguide-pulley I, mounted on a swinging post loosely set in said base Hand freely turning, as occasion requires, to allow the cord y to bebrought from any direction and to beled perpendicularly up the axis ofthe tube G to its connection with the link ,2, which is attached to thepin J, projecting from the sliding cross-head through alongitudinal slotin the outer tube G. This slot corresponds to a somewhat wider openingin the inner tube.

The downward motion of the cross-head S and pencil-point D is producedby the cord y, which is connected with the valve-rod, the motion ofwhich is to be studied, using any one of the well-known devices toreduce the movement, if necessary, to bringit within the limits of theinstrument.

The return motion ofthe cross-head and pencil-pointD is prod uced by thespringL, one end of which is secured to a fixed part of the apparatusand the other end connected to the sliding cross-head by a cord ypassing over the pulley 1. Obviously the contractile force of the springL, which was drawn out by the downward motion of the cross head, willreturn the cross-head to its initial position as quickly as the tensionon the lower end of the cord is diminished.

The pressure of the pencil-point D upon the paper or card C is regulatedby the distance to which the screw N is turned in its supporting-post,which of course determines the distance through which the pencil D isallowed to move toward the card before its motion is arrested by theinner end of the screw N striking against the stud O. This screw mayalso be used as a handle to bring the pencil-point into contact with thecard or to remove it from contact at any time by revolving the outertube G about the inner tube. This can be elfected while the instrumentis in operation, since the moving cord is in the axis of the tube G, sothat the only effect of revolving the tube G is to slightly twist thethe cords y and y, which evidently will in no way affect the operationof the instrument.

WVhen it is desired to take the steam-pressure card and the valve-motioncard simultaneously, connection is made between the steam and thevalve-motion indicators by the link M, pivoted to a projection a fromthe rotating sleeve 1' of the steam-indicator, and to an arm aprojecting from the tube G. Obviously both pencil-points will be broughtto bear on the card and removed at the sameinstant by moving the handlejby grasping said handle with the hand and swinging the cylindricalchamber A and all its accompanying devices to the left and the right,respectively, when the link M is thus connected. \Vith the link Mdisconnected, as shown in Fig. 5 and by dotted lines in Fig. 4, eitherthe steam or the valve-motion diagram may be taken separately.

Many other devices for obtaining a reciprocating motion of thecross-head and the pencil-point D might be adopted in the place of theone shown in the drawings, the essential feature being that the motionshould be such that the movement of the pencil-point shall correspond tothe motion of the part whose action is to be studied and that thepencilpoint may be brought into contact with the card at the desiredmoment.

The operation of my improved indicator is as follows: The cylinder 0beingheld stationary by the catch 1;, a fresh card is wrapped around thecylinder and held in place by the clamp s, the pencil-pointsD and hbeingturned away from the card and the link M being attached, as shown inFig. 4. The catch U being then released, the card-bearing barrel at oncetakes up an oscillating rotation corresponding to the movements of theengine-piston, and as soon as the motion becomes steady thepencil-points are moved gently upin contact with the oscillating card aby the operator by means of the handle j, both pencils meanwhile beingmoved up and down by reason of their connection with the indicatorpistonand the engine-valve, respectively. As soon as the contact between thecard and the points takes place the latter begin to describe diagrams,one of which may be used as the groundwork for studying the action ofthe steam in the engine-cylinder in the usual manner and the other ofwhich can be used for studying the action of the valve with regard toactual points of admission,cut-ott, exhaust, compression, wire-drawing,&c., and the departure of the actual movements of the valve relative tothose of the piston from the theoretical motion. By making suitableconnections the relative motion of all the valves or of other parts ofthe engine may be studied, and by disconnecting the link M either steamor valve-motion diagrams may be taken separately, as above described.

To explain more clearly the use and action of this device, exactreproductions of diagrams actually drawn by the instrument are shown inFigs. 6 and 7.

In Fig. (3 is shown a series of curves made by the valve-motionindicator alone when applied to a high-speed engine having an automaticcut-off steam-valve gear controlled by a centrifugal governor andindependent ex haustvalves separately operated, (Porter- Allen.) Theindicator-pencil was connected with the steam-valve gear. From whatprecedes it will be understood that the horizontal movement or componentof any one of the curves at any point corresponds to the actual motionof the engine-piston, while the vertical movement or componentcorresponds to the actual motion of the steam-valve, and the curveitself therefore shows the relative motion of the valve with respect tothe piston of the engine. The entire series of curves shows the changesin the action of the valve-gear and valves when the load on the engineis increased from no load (interior curve) to maximum load (exteriorcurve.) The horizontal line 8 corresponds to the position of thesteamvalve when just opening or closing at one end of the cylinder, andthe line 9 indicates similar conditions at the other end of thecylinder. For any particular load the points of ad mission and cut-off1O 11 and the amount of valveopening for either end of the cylinder areclearly shown at 12 13, as well as the extreme travel of the valve at14C. These curves also show that the amount of lead in this case wasvery little at one end and practically nothing at the other, and thatthe form of valve gear secures nearly a constantlead with greatvariations of load. The departurein the general shape of the curves fromtrue ellipses shows the effect of angularity of connectingrod or ofconnecting parts of the valve-gear, and the slight flattening of thecurves at 17 and 18 indicates lost motion in the valve-gear.

In Fig. 7 are shown steam and valve-motion diagrams taken simultaneouslyfrom an automatic cut-off higlrspeed engine of the slidevalve type, inwhich the valve is operated by a shifting eccentric and the cut-off iscontrolled by a fly-wheel governor, (New York Safety.) The intersectionsof the valve-motion diagram with the horizontal line 19 correspond tothe points of ad mission and cut-off, and its intersections with thehorizontal line 520 show the points of exhaust and compression. As inthe previous case, the amount of steam opening 21 and the extreme throwof the valve 22 are shown.

The fall of the steam-line and the rounded form of the steam-diagram atpoint of cut-oh? 23 are at once explained by the too-small steam-openingot the valve audits slow closure.

The latter is shown by the very oblique direction of the valve-motioncurvewith respect to the horizontal line at the point of intersection21. The opening of the exhaust 24 was fairly prompt and its closure 25was even more so. The shape of the valve-motion curve shows clearly, asin the former case, the eifects of angularity of connecting andeccentric rods, as well asthe irregularities produced by the action ofgravity on the weights of a centrifugal governing-valve gear revolvingin a vertical plane. These causes in this case have increased thecurvature of the lower half of the curve and flattened the upper part,producing corresponding changes in the points of cut-0E, exhaust, andcompression.

It is obvious that the instrument may be applied to any other form ofengine or valvegear and that it may be used in connection with a varietyof other machines besides steam-engines.

Persons skilled in the art will readily appreciate the advantages whichwill arise from the use of the apparatus as above indicated.

I claim as follows:

A valve motion indicating attachment for steam-engines, which comprisesa reciprocating pencil-carrying device, a revolving tube upon which saiddevice is mounted, the valve, devices which connect said pencil-carryingdevice with the valve of the engine, which said valve communicatesmotion in one direction to the pencil-carrying device, a spring whichcommunicates motion in the opposite direction to said pencil-carryingdevice, and devices which turn said tube and bring said pencil-carryingdevice into or away from contact with the card on which diagrams are tobe drawn, substantially as shown, and for the purposes specified.

JOHN MILLIS. Witnesses:

J. D. SCHMIDT, R. L. PRESTON.

